Regular Expressions 101

Explanation

Pro

Character Class[+]?

?matches at most one character from the set below:

+the literal + (43₁₀ / 53₈ / 2B₁₆)

Negative Lookbehind(?<!\d)

\da digit

Negative Lookbehind(?<!\d[ -])

\da digit

Character Class[ -]

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Non-Capturing Group(?: ((\d{1,2}[ -]?)?[(]?\d{3}[)]?[ -]?) (\d(?:[ -]?\d){3,6}) )

Group 1((\d{1,2}[ -]?)?[(]?\d{3}[)]?[ -]?)

Group 2(\d{1,2}[ -]?)?

?repeats the group contents below at most once:

\d{1,2}a digit, repeated between 1 and 2 times

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[(]?

?matches at most one character from the set below:

(the literal ( (40₁₀ / 50₈ / 28₁₆)

\d{3}a digit, repeated exactly 3 times

Character Class[)]?

?matches at most one character from the set below:

)the literal ) (41₁₀ / 51₈ / 29₁₆)

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 3(\d(?:[ -]?\d){3,6})

\da digit

Non-Capturing Group(?:[ -]?\d){3,6}

{3,6}repeats the group contents below between 3 and 6 times:

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\da digit

Negative Lookahead(?![ -]?\d)

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\da digit

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Unit Test Summary

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Quick Reference

25 tokens

Regular Expression

[+]?(?<!\d)(?<!\d[ -])
(?:
  ((\d{1,2}[ -]?)?[(]?\d{3}[)]?[ -]?)
  (\d(?:[ -]?\d){3,6})
)(?![ -]?\d)

Unit Tests

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